An online publishing system may receive listings from multiple users where each listing describes an item to be sold. The items may range from standard, mass-produced goods to one-of-a-kind or unique items. When many listings have been received, it may be difficult for a potential buyer or other sellers to navigate through and search for relevant listings. While some organization may be provided within the online publishing system, it may be haphazard and/or incomplete. Further, the organization within the online publishing system may not be flexible enough to incorporate new products.